This relates generally to isolation structures used in semiconductor devices.
Isolation structures are widely used in semiconductor devices. One general application is to isolate active areas from each other. In other cases, individual devices, rows of devices, or arrays of devices may need to be electrically isolated from other structures.
Conventionally, isolation structures may be formed by growing an oxide. For example, in field isolation regions, an oxide is grown to isolate substrate regions from one another.
In memory devices in particular, trench isolations are widely used. The trench isolation fabrication may begin by forming a trench and then depositing oxide, such as high density plasma (HDP) oxide, within the trench, in a step called trench filling. Both shallow trench isolations and deep trench isolations are known.
One problem with trench isolation structures is that voids may form in the filling process. The greater the aspect ratio of the trench, the more likely it is that voids may form. Voids may result in improper filling, and ineffective isolation.